The passive constitutive equation for muscle has been predominately handled in the past by discrete elastic and viscous elements. Y. C. Fung presented a quasi-linear theory of viscoelasticity using hereditary integrals. The intent of this research is to determine the total constitutive relations for dynamic conditions for muscle by proper combination of the known anatomic elements. Collagen fibers have been previously investigated and the results of this investigation are used to develop interactive conditions with the muscle fibers. Material constants are obtained from stress relaxation tests and quasi-static curves and verified by strain and the tetanic curve has been generated and stimulus parameters have been isolated. All experimental results are for the right anterior gracilis muscle of Sprague-Dawley rats.